As is well known, frequency bands commonly used in commerce at present include eight frequency bands in total, such as a Global System for Mobile Communication (GSM), GSM850 (824 MHz to 894 MHz), GSM900 (880 MHz to 960 MHz), a Global Positioning System (GPS) (1575 MHz), digital video broadcasting (DVB)-H (1670 MHz to 1675 MHz), a data communications subsystem (DCS) (1710 MHz to 1880 MHz), a personal communications service (PCS), a Universal Mobile Telecommunications System (UMTS) or a 3rd Generation Mobile Communications technology (3G) (1920 MHz to 2175 MHz), and Bluetooth or a Wireless Local Area Network (WLAN) 802.11b/g (2400 MHz to 2484 MHz). In addition, a Long Term Evolution (LTE) project is a currently popular operating frequency band, and operating frequency bands thereof include 698 MHz to 960 MHz and 1710 MHz to 2700 MHz.
An antenna is an apparatus used by a radio device to receive and transmit an electromagnetic wave signal. As the fourth generation mobile communications comes, there is an increasingly high requirement for a bandwidth of a terminal product. Because the antenna implements both signal propagation and energy radiation based on resonance of a frequency, an electrical length of the antenna is one fourth of a wavelength corresponding to a resonance frequency of the antenna, and terminal products at present become lighter and slimmer, how to design an antenna in smaller space is a problem to be urgently resolved.